1. Field of the Invention
The present invention relates to a process for preparing a copolymer latex and use of said copolymer latex. More particularly, the present invention relates to a process for preparing a latex of a copolymer comprising an aliphatic conjugated diene monomer and at least one other monomer copolymerizable therewith and a use of said copolymer latex in an adhesive composition, a paper coating composition, and an adhesive composition for adhering a lining to a carpet and for a rock fiber substrate.
2. Description of the Related Art
It is known that a so-called butadiene base copolymer latex is widely used as a binder in a paper processing field or back-sizing of a carpet.
The copolymer latex is required to have diverse properties according to application fields. To this end, in general, a composition and a structure of the butadiene base copolymer latex are modified.
A copolymer latex is usually prepared by emulsion polymerization, and during the emulsion polymerization, fine coagula are formed though an amount of the fine coagula slightly varies with a composition of a monomer mixture, and kinds and amounts of additives.
Recently, in view of labor saving and rationalization, speeds in paper coating and printing are being increased, and a coating color which is durable to high speed coating and a coated paper which is durable to high speed printing are required.
That is, the coating color is required to have stability against mechanical shear as a property to be satisfied during coating, and the coated paper is required to have an adhesive strength, water resistance and blister resistance.
It is known that a copolymer latex which is one of components of the coating color has a large influence on these properties.
One of factors which deteriorate the mechanical stability of the coating color is fine coagula in the copolymer latex. When the copolymer latex contains a large amount of such coagula, there arise various problems such as streak trouble or stain of an applicator during blade coating, stain during calendering, and blanket piling during printing.
The copolymer latex can be used as an adhesive for a lining of a carpet such as tufted carpet or needle punched carpet, or as an adhesive for a rock fiber substrate which is used in a cushioning material for automobiles, a mat for construction or an industrial filter. In such applications, the fine coagula in the copolymer latex have adverse influence on the adhesion strength and water resistance.
In general, the fine coagula are removed by, for example, filtration since they contaminate a reactor and cause problems in various final applications of the copolymer latex. However, since the filtration procedure is very complicated, and an amount of the coagula which can be removed by the filtration is limited, it is almost impossible to completely remove the fine coagula, and productivity of final products is decreased.